Darrell Castle joins race for White House representing party that has never won a seat in House or Congress.

A small US right-wing party has picked its nominee for the 2016 presidential race, hoping to lure disillusioned Republican voters.

Delegates nominated Darrell Castle as the party's candidate at their convention in Salt Lake City on Saturday.

"If I am elected president, I will first of all get out of the super-national authority, the United Nations," Castle said.

He also vowed that he would have the US leave NATO and promised to "end the Federal Reserve".

He added: "[We'll have] a different monetary system. By that I just mean - no more going to the king's table for his scraps. No more crying and begging for an audit of this bank, please-tell-us-what-you-did-with-our-money kind of thing," he said.

Castle, 67, also said he would deal with state debt in order for the US to stop being "a slave to the creditors" - but did not elaborate on how he would do that.

Pushing their agenda

The Constitution Party is one of the larger so-called "third-parties" fielding a candidate in the race to the White House.

"There is a growing sense among some Republicans that the Republican Party no longer represents them, that America is in decline."

Yet, Culhane said, the challenge for the Constitution Party is that very few people are aware of its existence, which makes fundraising difficult.

"It is going to be an uphill battle," she said.

The Constitution Party has never won a seat in either House of Representatives or Congress. It believes the US is a Christian nation founded on the basis of the Bible.